BRUSSELS -  NATO Secretary-General Jens Stoltenberg said Taliban bases in Pakistan pose a “big challenge” to efforts aimed at bringing peace and stability to Afghanistan.

Stoltenberg told reporters Tuesday at the alliance’s headquarters in Brussels that he regularly raises the issue in meetings with Pakistani leaders and will continue to do so. “We have to address the big challenge that Taliban are working also out of bases in Pakistan. And we have raised that several times. It is extremely important that all countries in the region support efforts of the Afghan national unity government and that no country provide any kind of sanctuary for the terrorists,” said the NATO chief.

Stoltenberg insisted if regional countries deny sanctuaries to insurgents the fight against the Taliban and terrorist groups in Afghanistan “will gain so much.” Responding to a question, he said NATO will boost its training mission in Afghanistan by around 3,000 troops.

The overall size of NATO's training and support mission in the unrest-hit country will increase from roughly 13,000 to roughly 16,000, he said.

Stoltenberg said the alliance would boost its presence "to help the Afghans break the stalemate, to send a clear message to Taliban to the insurgents that they will not win on the battleground". "There will be more troops. Current level is around 13,000, the new level will be around 16,000," he added.

But Stoltenberg insisted there would be no return to combat operations. "We are focusing on training the Afghan special operations forces, which have proven so key in the fight against the insurgents," he said.

A diplomatic source told AFP that the US would contribute 2,800 extra troops to the mission and other allies and partners around 700.